A British gay couple who won a landmark legal victory to father surrogate twins in America could now be forced to go through a lengthy adoption process in the UK.

British immigration officials told Barrie Drewitt and Tony Barlow when they arrived back in the UK last week that the three-week-old babies do not qualify for automatic residency.

The passports of twins Saffron and Aspen were confiscated and they were granted one month's temporary stay in Britain while Mr Barlow, 35, and Mr Drewitt, 32, planned their next step.

The twins, born in a Californian hospital in early December, were conceived using donor eggs from one woman, and sperm from one of the men - they have not revealed whom - and carried by a second woman, Rosalind Bellamy.

Aspen and Saffron: American passports

The two millionaire businessmen spent £200,000 ($322,000) on the surrogacy and are named on the twins' US birth certificates as "parent one" and "parent two". Reacting to the news, they said they were exasperated by the development.

Mr Barlow said: "We've been through so much before just to get pregnant and then worrying all through the pregnancy.

"All we want to do is just get on with our lives."

But a Home Office spokeswoman said the surrogate mother was still the legal parent of the babies under British law.

'No guarantee'

She said Mr Barlow and Mr Drewitt could apply for an extension to the month-long temporary stay to begin an attempt to adopt the children.

But there was no guarantee they would be granted adoption rights or how long the process would take, she said.

Another option would be to ask Home Secretary Jack Straw to intervene and grant the children residency under the British Nationality Act of 1981.

The fathers with surrogate mother Rosalind Bellamy

But the spokeswoman said Mr Straw would be wary of setting a precedent which could later be regretted when applied to other child immigration cases.

The third option would be to apply for entry clearance rather than citizenship for the twins - which would mean they would remain American nationals, but would be allowed to live in the UK.

The spokeswoman said: "With any case that raises unprecedented issues we would want to be careful to consider the implications.

Legal restrictions

"The welfare of the children has to be taken into account. We have to be careful the case would not set a precedent that would have unfortunate consequences."

The men's lawyer, Alison Stanley from Geoffrey Bindman and Partners, has told them that under UK law, British citizenship can only pass through a father if the father is married to the mother.

However, if either of the two men adopted the children they would automatically acquire British citizenship.

Mr Barlow and Mr Drewitt say they believe the case could be discriminatory against the children of gay couples and could be taken to the European Court of Human Rights.